Minnesota State University, Mankato, announced Monday that it will conduct a national search for a football coach to replace Todd Hoffner, who was removed from the job late last month after being cleared of child pornography charges stemming from cellphone videos he took of his children.

The announcement, six months after the school gave Hoffner a significant raise and a new four-year contract, comes 10 days after university officials informed him by letter that he would not be reinstated and was being reassigned to a job as assistant athletic director for facilities development.

Hoffner, the school's head football coach since 2008, was attending a coaches convention in Nashville on Monday and could not be reached for comment.

But the union and attorney who represent him have said they are determined to fight his reassignment and a 20-day, unpaid suspension that was to begin this week.

School officials, citing privacy laws, have declined to discuss the nature of the investigation into Hoffner or why he was suspended. A source with knowledge of the suspension has said that it is related to Hoffner's use of a school-issued cellphone to record the videos of his children playing and dancing naked after a bath. Those images led to the criminal charges.

"MSU can search all they want, but we intend to have Todd Hoffner reinstated as the head coach before the next season," said Chris Madel, a civil attorney who represents Hoffner. "They have a contract with him and we intend to make sure they live up to it."

Connie Howard, an attorney with the Inter Faculty Organization, which represents the faculty at state universities, said last month that the union filed a grievance challenging the suspension.

Howard did not return phone calls Monday.

In announcing its decision to find a new coach, MSU said that Aaron Keen, an assistant coach who guided the Mavericks to a 13-1 record and a berth in the NCAA Division II national semifinals in Hoffner's absence last fall, will serve as interim coach. The school said in a news release that Keen, who was also attending the coaches convention in Nashville, will continue in that role through the end of the current school year while a search for a permanent replacement takes place.

Keen, hired by Hoffner as an offensive coordinator making $56,265, will be paid an annual salary of $101,109, the same sum Hoffner earned.

"I am confident of Coach Keen's ability to direct our program and look forward to his continued leadership in this role," athletic director Kevin Buisman said in a news release.

Hoffner, 46, was arrested and charged in August on two felony counts of child pornography for videos he shot of his three children, ages 5 to 9, as they performed skits after taking a bath in the family's whirlpool tub in June. School officials discovered the videos after Hoffner turned in his malfunctioning cellphone to the university's IT department.

The university immediately put Hoffner on paid administrative leave pending the outcome of the criminal case and a university investigation. As part of the leave, Hoffner was not allowed to set foot on campus or attend his team's games.

From the outset, Hoffner's criminal attorney, Jim Fleming, and Hoffner's wife, Melodee, said that the images were taken out of context and were merely private family moments that showed nothing sexual or graphic.

In late November, after viewing the videos, Blue Earth County District Judge Krista Jass agreed. She dismissed the charges against Hoffner, saying the images were not pornographic and showed nothing more than innocent child's play.

Despite the ruling, the university continued to investigate.

University spokesman Dan Benson said Monday that the investigation is not yet complete.